feat(utils): add utility for define validator

mod.ts

@@ -70,6 +70,6 @@ export {
   validDate,
   value,
 } from "./factories.ts";
-export { lazy } from "./validators/utils.ts";
+export { defineValidator, lazy } from "./validators/utils.ts";
 export { type TypeStr, TypeValidator } from "./validators/operators/typeof.ts";
 export { type Constructor } from "./deps.ts";

validators/utils.ts

@@ -22,6 +22,28 @@ export abstract class BasicValidator<In = unknown, A extends In = In>
   abstract validate(input: In): Iterable<ValidationFailure>;
 }
 
+/** Create {@link Validator} from {@link Validator.validate}.
+ *
+ * @example
+ * import { defineValidator } from "https://deno.land/x/abstruct@$VERSION/validators/utils.ts";
+ *
+ * const StringValidator = defineValidator<unknown, string>(function* (input) {
+ *  const typeOf = typeof input;
+ *  if (typeOf !== "string") {
+ *    yield { message: `should be string, actual ${typeOf}`, instancePath: [] };
+ *  }
+ * });
+ */
+export function defineValidator<In, A extends In = In>(
+  validate: (input: In) => Iterable<ValidationFailure>,
+): Validator<In, A> {
+  class Validator extends BasicValidator<In, A> {
+    validate = validate;
+  }
+
+  return new Validator();
+}
+
 /** Crate validator lazily.
  *
  * @example

validators/utils_test.ts

@@ -1,6 +1,6 @@
 // Copyright 2023-latest Tomoki Miyauchi. All rights reserved. MIT license.
 
-import { BasicValidator, IsValidator, lazy } from "./utils.ts";
+import { BasicValidator, defineValidator, IsValidator, lazy } from "./utils.ts";
 import { TypeValidator } from "./operators/typeof.ts";
 import { ValidationFailure } from "../types.ts";
 import {
@@ -65,3 +65,13 @@ describe("IsValidator", () => {
     assertEquals([...new V().validate("")], []);
   });
 });
+
+describe("defineValidator", () => {
+  it("should return validator", () => {
+    const validate = () => [];
+    const validator = defineValidator<string, "a" | "b">(validate);
+
+    assert(validator.validate === validate);
+    assert(validator.is(""));
+  });
+});